Far from giving you a perfect body and inner calm, yoga could leave you with back ache and a groin strain.

The number of people who have taken up yoga has increased hugely in recent years.

But doctors and physiotherapists are reporting an upsurge in the number of inexperienced studients getting injuries after straining to get into difficult positions.

The British Wheel of Yoga, the governing body in the UK, has blamed a lack of properly trained instructors.

It believes that only half the estimated 10,000 people who now teach yoga in the UK are properly qualified.

The BWY recommends that instructors should complete a four-year training course before they start to school others in the ancient discipline.

However, it says that some sports centres are employing trainers who have completed just a month-long course.

Common injuries

The most common yoga injuries are caused by repetitive strain or overstretching and occur at the wrists, shoulders, neck, along the spine, and at the sacroiliac joint (which links the spinal column and pelvis), hamstrings, and knees.

Jayne Hill, a spokesperson for the BWY, told BBC News Online: "Yoga is the same as any other exercise discipline. It is perfectly safe if taught properly by people who understand it, and have experience.

"However, we are concerned that not all teachers are qualified, and that some people may be trying to cash in on the popularity of yoga."

Ms Hill said part of the problem was that new recruits may be tempted to push themselves too far because they were competitive about what they could achieve.

"A good teacher will get people out of that mindset," she said.

Regulation

Keith Waldon, vice chair of the Society of Sports Therapists, told BBC News Online that yoga should be tightly regulated.

He said: "A lot of people take up yoga thinking it is a gentle activity that will not cause them any harm, but that is not necessarily the case.

"People are putting themselves into positions that their bodies are not ready for, and this is causing muscle strains and pinched nerves."

Mr Waldon agreed that leaning how to teach yoga required a lengthy period of study.

"People need to learn about anatomy, physiology and what they are asking the body to do."